Depends how competitive you are, it's not really a game for casual players.
Not sure how true this is. Certainly pre level 20 the game is quite different from above and a lot more relaxed. Team builder also now means you can focus on a role and not worry about some one else playing it.
Where it does get intense is on the ranked side but that's down to what you want to get out of the game
It's free so give it a go, currently it's the most popular pc game by a reasonable margin.